Subliminal suggestion during sleep may work.
Not to say, however, that there isnāt something to be gained from subliminal attention. At a conference, I once heard a speaker, who places prostheses in the mouths of cleft palate children, (a prosthedontist) discuss the success he had had with subliminal suggestion. His job was to fit four year old cleft palate children, for whom surgery would not work, with an artrificial palate.
This palate consisted of a small turtle shell like plate with a small bulb which extends into the back of the throat (where the naso- pharyngeal port would have been (see a picture of one in the graphic version).